Electrical apparatus.



G. J. E. WAXBOM.

ELECTRICAL APPARATUS.- APPLI GATION FILED JAN.26, 1911.

Patented Dec. 31, 1912.

witmooca UNITED "STATES PAT NT OFFICE.

- CARL J. E. 'WAZBOH, OF COLUMBUS, OHIO, ASSIG-NOB THE JEFFREY MANUFAO mixture.

TUBING COMPANY, A CORPORATION OFOHIO.

ELECTB ICAL APPARATUS.

To all whom it'may concern." 1 4 Be it known that I, CARL J. E. WAXBOM, citizen of the United, States, residing at Columbus, in the county of Franklin and State of Ohio, have invented certain new and useful Improvements in Electrical Apparatus, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to improvements in electric motors or other electrical devices.

The particular object of the invention isto provide a motor or similar device which may be. used wlthout danger in mines, such as coal mlnes or other places 1n whlch an atmosphere of explosive gases is likely to be met with.

It is well known that in many cases disastrous explosions have been brought about by the use of electrical apparatusof various kinds in'connection with which precautions had not been taken to prevent explosive gases from having free access to those parts of the electrical .-.devicesat"which sparks frequently 'occur. Protecting devices of various sorts have been heretofore proposed for electrical apparatus. One of the most successful of these heretofore proposed pro tecting devices comprises a substantially flame and gas proof casing for inclosing the motor or other electrical device and a relief vent consisting ofan outward opening puppet valve, across the opening of which there is'placed one or more sheets of metallic gauze. As has been stated, the casing 1s sub stantially gas proof, and, therefore, there is little or no opportunity for external gases to find their way in tovform'an explosive However, if by any chance, an explosive mixture is formed and an explosion occurs itwill be relieved by the passage of the expanded gases out through the puppet valve. The metallic gauze prevents the passage of flame through the puppet valve to Ignite the external atmosphere. Protecting devices such as I have just described have been extensively tested by fill- .ing the casing with an explosive mixture and artificially igniting it. These tests have indicated that as an additional precaution it is advisable that the volume of gas within the casing which may be exploded should be as small as possible. When the amount of gas to be relieved through the puppet valve and the gauze is small there is less tendency Application filed January 26, 1911. Serial No. 604,810.

to injure the gauze and consequently greater safety results. 1 One of the object-s of my invention, therefore, is to provide an improved structure Patented Dec. 31, 1912.'

machine having a motor embodyingmyiin;

vention. """It "will .be -understood'fhowever, that my invention is not limited to the par ticular form of motor shown, but is to be considered as applicable to any form of electrical device in connection with which sparks are likely to occur.

Of the drawings, Figure 1 is a longitudinal cross sectional view of a motor embodye ing my invention. Fig.- 2 is a transverse cross sectional view of the motor taken along the line 22 of Fig. 1. Fig. 3 is a detail cross sectional view of one of the relief vents.

The motor which I have shown for purposes of illustration is of the type in which the casing is integral with and in fact forms the field poles. The pole pieces are indicated in the drawings by 5, 5.

6, 6, represent the field coils.

7 represents the main or armature shaft of the motor. This is mounted in bearings 8 and 9.

10 represents a pinion on the shaft through which power is transmitted to a mining machine or other device to be driven.

.11 represents as a whole the rotor which is mounted upon' the shaft 7. This rotor comprises the armature l2 and the commutator 13-.

14 represents one of the brushes which en- I I metallic framework 16. This framework is y to place the relief devices near the brushes.

removably secured in position over an opening in the casing. 17 is a door or cover pivotally mounted upon the frame 16. This serves to protect the glass frominjury.

The casing of the motor is provided at proper points, preferably at point-s adjacent the brushes, with relief vents or devices which are indicated as a whole by 18. Each of these devices is located at an aperture in the casing and comprises a valve seat 19, a valve 20 adapted to rest upon the seat to close the aperture-in the casing, a frame or spider 21, a guide pin 22 connected with the valve and slidable in the spider, and a spring 23 surrounding the pin 22 and serving to normally hold the valve upon its seat. Across the aperture of the valve are provided a number, in this case three, of perforate metallic sheets, which may be either wire gauze or perforated sheet metal. These are indicated in the drawings by 24:, 24. They are separated by spacing rings 25, 25, the

inner of the rings being held in place by an expansible split ring 26 which engages a groove in the inner surface of the aperture through the valve seat 19.

As indicated in Figs. 1 and 2 by a at various points the spaces within the motor casing, which would be otherwise open, are

filledrwith a packing which may preferably be composed of asbestc wor other --suitabla material mixed with cement and applied to the motor in a more or less plastic condition, being afterward allowed to harden. initially plastic substance is used to fill every available space within the casing, the spaces within the rotor being filled as well as those surrounding it. It is, of course, understood that a proper working clearance is .left between the moving and the stationary parts.

As a practical matter it is, of course, necessary to leave an appreciable open space around the brushes. This is necessary in order to permit inspection of them through the window 15 and also to permit their adjustment from time to time. On account of the necessity for a relatively large open space adjacent the brushes, it is found preferable to locate the relief devices 18 as close as possible to this open space. It will be observed that should an explosion be caused within the casing combustion will start at or near the brushes. The tests to which I have heretofore referred have shown that there is less likelihood of damage resulting to the relief devices when they are located near the point at which combustion starts. For this reason also it is, therefore, desirable bestos, as it will be apparent that any plastic non-magnetic non-combustible material may be used. essarily limited to plastic material as certain of the advantages incident to my invention may be secured by the use of blocks of suitable material properly secured in place.

It is to be noted that my invention is applicable to any motor which has a substantially flame proof casing and is not necessarily limited to motors especially designed with my invention in View. Even in new designs, however, it will be found advantageous to reduce the open space within the casing by means of plastic compounds such as contemplated by me'instead of attempting to reduce the open space by changes in or additions to the metallic parts of the motors.

What I claim is:

1. In an electrical device, the combination with elements in connection with which sparks are likely to occur and a substantially gas proof casing surrounding the said elements and having spaces unoccupied by them, of a hardened initially plastic mass of non-magnetic material distributed throughout the casing to fill the major portion of the space therein which would otherwise be open.

2. In an electrical device, the combination with elements in connection with which sparks are likely to occur and a substantially gas proof casing surrounding the said elements and having spaces unoccupied by them, of non-magnetic material distributed throughout the casing to fill the major portion of the space therein which would otherwise be open.

3.- In an electrical device the combinationwith elements, some movable and some stationary, in connection with which sparks are .likely to occur, and a substantially gas proof ing 'not only outside the said movable ele-.

ments but also within the outlines thereof.

In testimony whereof I ailix my signature,

in presence of two witnesses.

CARL J. E. WAXBOM.

Witnesses:

Nnim HUNTER, a

F. E. V N'SLYK;

In fact, my invention is not nec- 

